1. Field of the Invention
The invention relates generally to a method and system for an improved computerized, automatic segmentation of the lung regions in lateral chest radiographs. Novel techniques in the segmentation of the lung regions include adaptive local thresholding.
The present invention generally relates to CAD techniques for automated detection of abnormalities in digital images, for example as disclosed in one or more of U.S. Pat. Nos. 4,839,807; 4,841,555; 4,851,984; 4,875,165; 4,907,156; 4,918,534; 5,072,384; 5,133,020; 5,150,292; 5,224,177; 5,289,374; 5,319,549; 5,343,390; 5,359,513; 5,452,367; 5,463,548; 5,491,627; 5,537,485; 5,598,481; 5,622,171; 5,638,458; as well as U.S. applications Ser. Nos. 08/158,388; 08/173,935; 08/174,175; 08/220,917; 08/393,779; 08/398,307; 08/428,867; 08/523,210; 08/536,149; 08/536,450; 08/536,794; 08/515,798; 08/562,087; 08/673,502; 08/757,611; 08/758,438; 08/900,191 filed Jul. 25, 1997; Ser No. 08/900,361 filed Jul. 25, 1997; Ser. No. 08/900,362 filed Jul. 25, 1997; Ser. No. 08/900,188 filed Jul, 25, 1997; and Ser. No. 08/900,192 filed Jul. 25, 1997. The present invention includes use of technologies referenced and described therein, as well as described in the references identified in the appended APPENDIX and cross-referenced throughout the specification by reference to the number, in brackets, of the respective reference listed in the APPENDIX, the entire contents of which, including the related patents and applications listed above and references listed in the APPENDIX, are incorporated herein by reference.
2. Discussion of the Background
Although a conventional radiographic chest examination consists of both posteroanterior (PA) and lateral projections, the use of the PA image for current digital image processing techniques is a logical approach. In contrast to the lateral image, the PA image demonstrates well-defined anatomic borders, especially along the lung apices, lateral margins, diaphragmatic borders, and cardiac silhouette. The mediastinal/lung interface is also clearly defined in the PA image. The PA configuration projects each lung field to a distinct region of the film, while the lateral projection superimposes information from both lungs and from mediastinal structures to essentially the same location on the film. Accordingly, the PA radiograph is generally more sensitive for the detection of lung pathology.
However, despite these differences, the clinical utility of the lateral radiograph is well-established [1-7]. The lateral view often provides important diagnostic information that contributes to clinical diagnosis. Computer-aided diagnostic (CAD) schemes are likely to benefit from the clinically relevant radiographic information contained in lateral images. It is quite conceivable that proper segmentation of the lung region from lateral chest images could lead to the development of a new spectrum of CAD methods while contributing another dimension to current CAD schemes. For example, radiographic characteristics of the retrosternal clear space and the retrocardiac region of lateral chest images could be automatically analyzed to assess conditions such as emphysema, cardiomegaly, or pleural effusion, or nodule candidates selected by current PA-image-based lung nodule detection schemes could be confirmed based on analysis of corresponding regions in the lateral image.
Accordingly, an object of this invention is to provide a method and system for segmenting lung regions in lateral chest images.
Another object of this invention is to provide an automated method and system for the adaptive local thresholding of images.
These and other objects are achieved according to the invention by providing a new and improved automated method and system in which a segmentation of lung regions within a lateral chest image is performed.